The present invention relates to hinges, and in particular to a hinge with an adjustable counterbalance spring for use on vehicles.
Manufacturers often utilize a spring assist to counterbalance the weight of a hinged vehicle body panel where the body panel is intended to be lifted by an operator, such as in the case of a vehicle trunk lid or deck lid. However, the panels used on different vehicles vary in weight, thus requiring that either an inventory of different hinge/spring subassemblies with different counterbalance forces be used or that a particular hinge/spring subassembly work on all vehicles. In the first case, manufacturers are becoming increasingly concerned over the proliferation of parts and the resulting increases in inventory carrying costs, assembly line space problems, and quality problems due to mis-builds. Thus, there is strong resistance toward merely adding parts to cover the need for different hinge/spring assemblies. In the second case, it is difficult to design one hinge/spring subassembly that satisfactorily works on all vehicles. This is due to the varying weight of deck lids which vary not only between car-lines, but also within a given car-line depending upon vehicle options and normal part weight variation.
One potential solution is to provide a hinge with an adjustable counterbalance force. At least one manufacturer has done so, utilizing a system of torsion rods that are adjustable in tension. However, this arrangement is somewhat bulky, and requires more installation labor than is desirable. Further, improvements are desired in cost and weight.
At least one manufacturer has chosen to build hinge/spring subassemblies with a spiral coil spring preassembled to the hinge. This provides a compact subassembly that can be attached to the deck lid and vehicle without the need for subsequent installation of a counterbalance spring assist. However, while this arrangement is compact, the counterbalance force of the hinge assembly is not adjustable.
Where possible, it is desirable to subassemble the counterbalance spring to the hinge before the assembly to the vehicle, thus eliminating the need for a separate installation of the counterbalance spring to the vehicle. However, such a hinge if adjustable must be adjustable quickly, safely, on-line, and with a minimum of manpower and effort. This is difficult given the typical attachment position of the deck lid hinge which is located under the rear window and rear shelf of the partially assembled vehicle.
Therefore, a new or improved adjustable tension hinge is desired.